Polymerization of ethylene with a supported palladium catalyst

ABSTRACT

HYDROCARBON OLEFINS ARE CONVERTED TO HIGHER BOILING PRODUCTS COMPRISING POLYMERS AND OLIGOMERS OF THE OLEFIN AND ALKYLATES OF THE OLEFIN WITH PARAFFINIC HYDROCARBONS IN THE PRESENCE OF A GROUP VIII NOBLE METAL DISTENDED ON A SYNTHETIC ZEOLITE, I.E., AN ALUMINOSILICATE MOLECULAR SIEVE, THAT HAS BEEN PRETREATED WITH HYDROGEN AT CONDITIONS TO IMPART SELECTIVE POLYMERIZATION OR ALKYLATION ACTIVITY THERTO. IN A SPECIFIC EMBODIMENT, ETHYLENE IS POLYMERIZED TO LOW BOILING OLIGOMERS COMPRISING DIMERS, TRIMERS, TETRAMERS, ETC. BY CONTACTING THE ETHYLENE UNDER POLYMERIZATION CONDITIONS WITH A PALLADIUM CATALYST PREPARED BY IMPREGNATION OF A PALLADIUM SALT OR ION EXCHANGE OF PALLADIUM FROM A PALLADIUM SALT ONTO A Y MOLECULAR SIEVE THAT HAS BEEN PRETREATED WITH HYDROGEN AT A TEMPERATURE FROM ABOUT 200* TO 900*F. OR IS POLYMERIZED TO SOLID POLYMER WHEN THE HYDROGEN TREATMENT IS PERFORMED AT A TEMPERATURE FROM 0* TO 100*F. THE ETHYLENE IS ALSO REACTED UNDER ALKYLATION CONDITIONS WITH A PARAFFIN HYDROCARBON BY CONTACTING THE OLEFIN AND PARAFFIN UNDER ALKYLATION CONDITIONS WITH A PALLADIUM DEPOSITED ON A Y MOLECULAR SIEVE THAT HAS PRETREATED BY CONTACTING WITH HYDROGEN AT A TEMPERATURE OF FROM 100* TO ABOUT 200*F.

US. Cl. 260-943 DA 5 Claims ABSTRACT OF THE DISCLOSURE Hydrocarbonolefins are converted to higher boiling products comprising polymers andoligomers of the olefin and alkylates of the olefin with paraflinichydrocarbons in the presence of a Group VIII noble metal distended on asynthetic zeolite, i.e., an aluminosilicate molecular sieve, that hasbeen pretreated with hydrogen at conditions to impart selectivepolymerization or alkylation activity thereto. In a specific embodiment,ethylene is polymerized to low boiling oligomers comprising dimers,trimers, tetramers, etc. by contacting the ethylene under polymerizationconditions with a palladium catalyst prepared by impregnation of apalladium salt or ion exchange of palladium from a palladium salt onto aY molecular sieve that has been pretreated with hydrogen at atemperature from about 200 to 900 F. or is polymerized to solid polymerwhen the hydrogen treatment is performed at a temperature from 0 to 100-F. The ethylene is also reacted under alkylation conditions with aparafiin hydrocarbon by contacting the olefin and parafiin underalkylation conditions with a palladium deposited on a Y molecular sievethat has been pretreated by contacting with hydrogen at a temperature offrom 100 to about 200 F.

DESCRIPTION OF THE INVENTION This application is a continuation-in-partof copending application Ser. No. 760,724, filed Sept. 18, 1968, nowPatent 3,644,565.

The invention relates to the production of higher boiling products fromlow molecular weight olefins and in particular relates to a method forthe catalysis of the oligomerization of hydrocarbon olefins and/ or thealkylation of parafiins with hydrocarbon olefins.

The invention comprises the catalysis of the aforedescribed reactionusing a Group VIII noble metal supported on a metal aluminosilicatemolecular sieve, zeolite, wherein the catalyst is pretreated bycontacting with hydrogen at specified temperatures which impartsselective activity to the catalyst for the desired reaction.Specifically, the invention comprises contacting the catalyst withhydrogen at a temperature from about 0 to 100 F. to impartpolymerization activity thereto and then using the catalyst forpreparation of high molecular Weight poly olefins. The invention alsocomprises contacting the catalyst with hydrogen at a temperature from100 F. to about 200 F. to impart alkylation activity thereto andsubsequently employing the pretreated catalyst for alkylation reactions.The invention further comprises the pretreatment of the catalyst withhydrogen at temperatures from about 200 to about 900 F. and subsequentuse of the pretreated catalyst to cause polymerization of low molecularweight olefins. The products obtained from either reaction are useful asblending agents for motor fuels and as chemical intermediates, e.g., theoligomers of low molecular weight olefins can be used as substrates forthe formation of aldehydes, alcohols and acids via the 0x0 typereaction.

Various investigators have reported that molecular sieves or zeolites,which are synthetic aluminosilicates of a crystalline structure anduniform pore diameter, are

United States Patent 0 'ice active as catalysts for the polymerizationof hydrocarbon olefins and that such zeolites can also be used ascatalysts for alkylation of isoparaflins with hydrocarbon olefins. Inthese prior applications, the zeolites have not been used with a GroupVIII noble metal cocatalyst and the prior art attempts have notinvestigated the effect of hydrogen pretreatment of the zeolite prior touse in the desired reaction.

I have found that when the zeolite is activated by the incorporation ofa Group VIII noble metal thereon that the activity of the resultingcatalyst for alkylation and polymerization reactions is substantiallyaltered by the presence of the Group VIII noble metal in the catalyst.It is not known with certainty the mechanism by which the Group VIIInoble metal effects the activity of the molecular sieve, however it isbelieved that the presence of the Group VIII noble metal in the catalystdecreases the population of zeolitic acidic sites that would otherwisebe available as polymerization catalysts. It is not believed, however,that all of the anomalous activity of the zeolite in the presence of theGroup VIII noble metal can be explained by this phenomena since theamount of noble metal which can change the activity of the zeolite ismuch less than the stoichiometric equivalent of the acidic sites, e.g.,of the order of about 0.5 weight percent. The pres ence of the GroupVIII noble metal on the zeolite substantially deactivates the zeolitefor catalysis of polymerization or alkylation unless the catalyst ispretreated with hydrogen in the manner described hereafter.

The catalyst is treated in accordance with my invention by any of aplurality of hydrogen pretreatments which are effective to impartselective activity of the catalyst for polymerization of the olefin toeither high molecular weight solid polymers or to oligomers, or toimpart activity for alkylation of paraifins with the olefins.Specifically I have found that pretreatment of the molecular sieve bycontacting it with hydrogen for a period of from several minutes toseveral hours imparts activity for: (l) the polymerization of ethyleneto high molecular weight solid products when the pretreatment isperformed at a temperature from about 0 to F.; (2) imparts an activityof the catalyst for oligomerization of olefins when the pretreatment isperformed at a temperature of from 200 to 900 F.; and (3) imparts anactivity to the catalyst for the alkylation of paraffin hydrocarbonswith hydrocarbon olefins when the pretreatment is performed at atemperature from 100 to about 200 F.

The olefins that can be reacted in accordance with this inventiongenerally comprise the lower molecular weight aliphatic hydrocarbonolefins having from 2 to about 8 carbons; preferably those olefinshaving from about 2 to about 4 carbons. Examples of suitable reactantsinclude ethylene, propylene, butene-l, butene-2, isobutylene, pentene-l,isopentene, hexene-l, hexene-Z, isohexene, heptene-l, heptene-Z,heptene-3, isoheptene, 2-ethylhexene, octene, isooctene, etc. Of these,the alpha olefins and the olefins having from 2 to about 4 carbons arepreferred classes.

The paraffin that can be alkylated with the olefin in one embodiment ofthe invention can comprise any normal or iso parafiin having from 2 toabout 10 carbons. The catalyst exhibits an unusually high activity forthe alkylation of normal paraffins and accordingly the invention findsparticular application to the alkylation of this class of hydrocarbonparafiins. Examples of suitable parafl'ins that can be alkylated withthe olefin in accordance with my invention in general comprise ethane,propane, butane, isobutane, pentane, isopentane, hexane, Z-ethylhexane,heptane, isoheptane, octane, isooctane, decane, isodecane, nonane,isononane, etc. The alkylation aspect of the invention is particularlyapplicable to the alkylation of the low molecular weight parafiins thatare in surplus quantities at refineries, e.g., ethane, propane, butane,isobutane, etc., to convert these low molecular weight paraffins tohigher boiling hydrocarbons suitable for use as gasoline blending stock.

The catalyst for the reaction comprises a Group VIII noble metal whichis supported or distended on a zeolite. The Group VIII noble metal thatcan be employed can be any of the platinum groups such as platinum,iridium or osmium or any of the palladium subgroups, e.g., palladium,rhodium or ruthenium. Palladium is the preferred catalyst because of itsdemonstrated greater activity. The catalyst metal is employed supportedon a suitable zeolitic molecular sieve solid and can comprise from 0.05to about 5.0 weight percent of the final composition. The Group VIIInoble metal is impregnated on the catalyst or, in the preferredembodiment, is incorporated in the molecular sieve by an ion exchangereaction described hereinafter.

The substrate used for the catalyst comprises a dehydrated metalloaluminosilicate or zeolite which has a characteristic X-ray diffractionpattern and has pores of relatively uniform diameter from about 4 toabout 18 angstrom units. The silica and aluminum are in combination withone or more exchangeable cations such as sodium, hydrogen, magnesium orcalcium which are present as exchangeable cations on ion exchange sitesof the al-uminosilicate. The substrates, which have acquired a commonclassification in the art as molecular sieves, have silica to aluminaratios from about 2.5 to about 10 and the preferred substrates for usein this invention are those having ratios from about 3 to 8, and mostpreferably from about 4 to 6. The molecular sieves are commerciallyavailable in various designations such as A, X, Y, L, S and T, and ofthese the Y molecular sieves are preferred. These preferred molecularsieves have the aforementioned preferred silica to alumina ratios andhave the general emperical formula as follows:

wherein W is from 2.5 to about 6 and X is from to 9.

The molecular sieves are generally prepared with sodium or potassiumassociated with the ion exchange sites and the monovalent metal issubsequently ion exchanged with any polyvalent metal or can be ionexchanged with an ammonium salt. Heating of the resulting ammoniumcharged molecular sieve decomposes the ammonium ion and leaves thehydrogen ion associated with the ion exchange site and this treatment isa preferred treatment for preparation of the catalyst used in myinvention. The extent of the exchange of the monovalent metal with thepolyvalent metal or with the ammonium can be sufficient to remove from50 to 98 percent of the monovalent metal present in the molecular sieve;preferably from about 85 to about 95 percent removal is effected. Theammonium that is exchanged into the molecular sieve can thereafter beconverted, if desired, to hydrogen by heating of the sieve for a periodof 1 to 24' hours at a temperature of from 700 to about 1000 F.

The Group VIII noble metal can be incorporated in the molecular sieve bythe various techniques such as impregnation of the molecular sieve witha salt of a Gorup VIII noble metal by immersing the molecular sieve inan aqueous solution of the salt and dissolving the solvent or byprecipitating the Group VIII noble metal as an insoluble salt or oxidefrom the solution in the presence of the molecular sieve.

In a preferred technique, the Group VIII noble metal is incorporated inthe molecular sieve by ion exchange techniques such as that disclosed inU.S. Pat. 3,236,762 wherein the molecular sieve is digested with anaqueous solution of the noble metal salt under ion exchange conditionsto exchange the noble metal cation for the metal or ammonium ionoriginally present in the molecular sieve, separating the molecularsieve from the treating solution and thereafter reducing the noble metalcation on molecular sieve to its metal state by contacting with asuitable reducing agent such as carbon monoxide, hydrogen hydrazine,alkali metal borohydrides, alkali metal dithionites, etc.

The molecular sieves or synthetic zeolites can be prepared in accordancewith the method described in U.S. Pats. 2,882,243 and 2,882,244 which ingeneral involve digesting aqueous solutions of sodium silicate andsodium aluminate at elevated temperatures following low temperatureaging treatment. The preparation of the preferred catalyst, i.e., the Ytype zeolite, can be performed in accordance with the teachings of U.S.Pat. 3,239,471 which involves the initial low temperature aging of amixture of silica hydrosol, sodium hydroxide and sodium aluminate,followed by a high temperature digestion to effect crystallization ofthe sodium zeolite.

The microcrystalline zeolitic preicipitate formed in the aforementioneddigested step is thereafter dried by heating at ambient or lowtemperatures, e.g., up to about 300 F. to evaporate most of the watertherefrom to obtain a dry powder containing up to about 20 weightpercent water which can be readily handled by conventional techniquesfor the preparation of catalyst particles. This dry powder can be moldedand compressed with tableting machines or extruders to provide pelletedcatalysts that can be used in the reaction. Alternatively, the powdercan be subsequently calcined and used directly or ground to a state offurther subdivision for use in systems employing finely dividedcatalysts.

The catalyst particle size can vary over wide limits from about 0.5 inchto about 1 micron average diameter. The particle size selected dependson the type of solid-vapor contacting employed in the reaction zone. Adispersed gas phase reaction would employ the very fine particlespassing about a 325 mesh screen. Use of a fluidized bed reactor wouldrequire use of particles passing a 20 but retained on a 400 mesh screen.Packed bed reactors or liquid slurry phase reaction conditions would usethe larger diameter particles having diameters from about 0.05 to about0.5 inch; preferably from about 0.1 to 0.25 inch.

The catalyst in the desired particle size for use in the invention isthereafter subjected to final calcining in dry air at a temperature ofabout 800900 F. for several hours and this treatment when applied to thezeolites having ammonium exchanged thereon results in decomposition ofthe ammonium to the hydrogen form of the zeolite.

If desired, the catalyst during the pelleting operation can be admixedwith a suitable solid diluent, in a comparable particle size, such astitania, zirconia, alumina, silica, etc., or a combination of thesematerials in an amount from about 5 to about weight percent of the finalcomposition. Examples of suitable materials include the aluminumsilicates, synthetic or naturally occurring clays, or any of theaforementioned hydrous metal oxides.

The catalyst is activated for the desired reaction in accordance withthis invention by the pretreatment thereof with hydrogen at specifiedtemperatures which impart the desired selective activity to thecatalyst. The treatment can comprise contacting the catalyst withhydrogen at a hydrogen pressure of from about 0.5 to about 1000atmospheres with the total pressure of the contacting being from about 1to about 1000 atmospheres. If desired, the concentration of hydrogen inthe vapor phase during the treatment can be from about 10 to aboutpercent of the total vapor contacted with the catalyst. Suitable inertdiluents that can be used to dilute the hydrogen can include carbondioxide, nitrogen, or low molecular weight alkanes, e.g., methane,ethane, propane, etc. The contacting with hydrogen is performed for aperiod of from 10 minutes to five hours; preferably from one-half tothree hours; and simply comprises maintaining the catalyst at thedesired temperature in contact with the hydrogen containing gas phase.This can be performed in an oven wherein the catalyst is heated to thedesired temperature under hydrogen vapor or can be performed in thereaction zone itself by charging the catalyst to the olefin conversionreactor and introducing hydrogen o contact the catalyst at the necessarytemperature for activation.

The catalyst is activated in accordance with this invention by treatingwith hydrogen at temperatures selected to impart the desired activity tothe catalyst. When the catalyst is treated with the hydrogen containinggas as aforedescribed at temperatures from about to about 100 F., thecatalyst acquires activity for polymerization of the low molecularweight olefin to solid polyolefins of high molecular weight. When thepretreatment is performed at temperatures from about 100 to about 200F., the catalyst acquires the property for alkylation of parafiins withthe low molecular weight olefins aforedescribed. When the pretreatmentis performed at temperatures of from about 200 to about 900 F., thecatalyst acquires the activity for the oligomerization of the lowmolecular weight olefins to produce oligomers of intermediate molecularweight.

The catalyst after the pretreatment is used for the desired conversionunder conventional processing conditions, e.g., under liquid phase orvapor phase heterogeneous processing conditions. In vapor phaseoperations the catalyst can be employed as solid pellets packed in afixed bed reactor and the reactants can be introduced as a vapor streaminto contact with the packed catalyst bed. Alternatively, the catalystcan be employed as a finely divided powder dispersed in the reactantvapors in a disperse or dense solid or fluidized phase according toconventional processing techniques. The catalyst can also be employedunder liquid phase conditions as a slurry of the powdered or particulatecatalyst in a liquid reaction medium that can be an excess of thereactants employed or can be any suitable inert liquid. Various organicliquids that can be employed for this purpose include: sulfoxides,sulfones, amides, ketones, ethers or esters, carboxylic acids, etc.

Illustrative of this last class of liquids are: acetic, propionic,butyric, pentanoic, hexanoic, heptanoic, octanoic acids, benzoic,toluic, phthalic acids, etc. Of these, the fatty carboxylic acids havingfrom about 2 to about 8 carbons are preferred.

Other organic liquids that can be employed include the alkyl and arylsulfoxides and sulfones such as dimethylsulfoxide, propylethylsulfoxide,diisopropylsulfone, decylmethylsulfoxide, butylamylsulfone,diisooctylsulfoxide, diphenylsulfoxide, methylbenzylsulfone, etc.

Another class of organic liquids that are inert are various amides suchas formamide, dimethyl formamide, ethylisopropyl formamide, acetamide,n-phenylacetamide, N,N-dipropylacetamide, isobutyramide,N-ethylisobutylamide, isovaleric amide, N,N-dimethylisovaleric amide,isocaprylic amide, N,N-methyl-n-caprylic amide, N-propyl-n-heptanoicamide, isoundecyclic amide, etc.

Various alkyl and aryl ketones can also be employed as the reactionmedium, e.g., acetone methylethyl ketone, diethyl ketone, diisopropylketone, ethyl-n-butyl ketone, methyl-n-amyl ketone, cyclohexanone,di-iso-butyl ketone, etc.

Ethers can also be employed as the reaction medium, e.g., diisopropylether, di-n-butyl ether, ethylene glycol diisobutyl ether, methylo-tolyl ether, ethylene glycol dibutyl ether, diisoamyl ether, methylp-tolyl ether, methyl m-tolyl ether, dichloroethyl ether, ethyleneglycol diisoamyl ether, diethylene glycol diethyl ether, ethylbenzylether, diethylene glycol diethyl ether, diethylene glycol dimethylether, ethylene glycol dibutyl ether, ethylene glycol diphenyl ether,triethylene glycol diethyl ether, diethylene glycol di-n-hexyl ether,tetraethylene glycol dimethyl ether, tetraethylene glycol dibutyl ether,etc.

Various esters can also be employed as the reaction medium, e.g., ethylform-ate, methyl acetate, ethyl acetate, n-propyl formate, isopropylacetate, ethyl propionate, n-propyl acetate, sec-butyl acetate, isobutylacetate, ethyl n-butyrate, n-butyl acetate, isoamyl acetate, n-amylacetate, ethyl formate, ethylene glycol diacetate, glycol diformate,cyclohexyl acetate, furfuryl acetate, isoamyl n-butyrate, diethyloxalate, isoamyl isovalerate, methyl benzoate, diethyl malonate,valerolactone, ethyl benzoate, methyl salicylate, n-propyl benzoate,n-dibutyl oxalate, n-butyl benzoate, diisoamyl phthalate, dimethylphthalate, diethyl phthalate, benzyl benzoate, n-dibutyl phthalate, etc.

The reaction is performed under polymerization or alkylation conditions.The conditions generally include pressures from about 1 to about 1000atmospheres and temperatures from about 50 to about 500 F. Preferably,the reaction pressure is from about 10 to about 200 atmospheres and thetemperature is from about to about 300 F. The polymerization oroligomerization of the low molecular Weight olefin is achieved byintroducing the olefin into contact with the catalyst which is presentas a packed bed of solids in a reactor or is dispersed in a liquid orvapor phase reaction mixture. The alkylation is performed by introducinga mixture of olefin and paraflin into contact with the catalyst in asimilar processing. The reactant or reactants, if desired, can bediluted with suitable inerts such as the aforementioned carbon dioxideor nitrogen, or in the cases of polymerization and oligomerization, inthe presence of low molecular weight parafiins such as methane, ethane,propane, etc.

The recovery of the product from the reaction zone varies somewhat onthe nature of the particular conversion performed. When the product is asolid polyolefin, the reaction can be continued until the solid hasaccumulated in the reaction zone to a sufiicient quantity to warrantdiscontinuing the reaction and recovering the solid product therefrom.When liquid phase processing is employed, the organic reaction liquidcan preferably be a solvent for the particular polyolefin, e.g., theaforementioned paraffinic hydrocarbons can be employed as the reactionmedium, and a portion of the liquid phase can be continuously withdrawnfrom the reaction zone, the catalyst can be separated from the liquidphase, and the solvent evaporated to precipitate the solid polyolefin asa product of the reaction. The solvent and catalyst can be recycled tothe reaction zone to maintain the liquid and catalyst inventory therein.

When the products are relatively volatile under the reaction conditions,e.g., the oligomers of olefins or the various alkylates of the paraflinwith the olefin, the reaction can be performed under conditions whichstrip or vaporize the product from the reaction zone and continuouslyremove the product in the vapor phase. Alternatively, a portion of theliquid phase reaction medium can be withdrawn and the product can berecovered by conventional distillation from the liquid efiluent. Whenthe reaction is performed under entirely vapor phase conditions, theproducts are, of course, removed in the vapor eflluent from the reactionzone and can be recovered therefrom by condensation and subsequentfractionation.

In all of the various processing techniques, the vapor effluent from thereaction zone can be cooled to collect condensate therefrom and theunconverted hydrocarbon olefin and, during alkylation conditions,unconverted paraffin can be recycled by compressing and returning thesereactants to the reaction zone.

Various techniques can be used to maintain the desired temperature forthe reaction. The reactants can be preheated to the desired reactiontemperature and the temperature maintained in the reaction zone by useof a suitable heat exchange medium to remove or to add heat as requiredfor temperature maintenance. The use of a liquid reaction solventpermits the continuous refluxing of the reaction solvent to maintain thedesired reaction temperature by vaporizing solvent which is condensedand returned to the reaction zone. Alternatively, the reaction zonetemperature can be maintained by withdrawing a portion of the liquidphase and passing it through a heat exchanger to remove or add heat asnecessary to maintain the temperature. Various conventionally employedheat exchange means such as cooling coils can also be immersed in theliquid phase or imbedded in the packed catalyst bed contained within thereaction zone to permit circulation of the heat exchange fluid inindirect heat exchange relationship with the reaction zone contents tothereby maintain the desired temperature.

The reaction is performed until the activity of the catalyst has beendescreased sufficiently to justify regeneration of the catalyst. Therate of deactivation of the catalyst varies considerably with thedesired reaction, e.g., separation of a solid polyolefin frequentlyresults in rapid deactivation because of the occlusion or impregnationof the catalyst with the solid polymer product. To some extent this rateof deactivation can be reduced by performing the reaction in a liquidhaving a solvency for the polyolefin and this is a preferred technique.

When the catalyst has been deactivated sufficiently for regeneration,the catalyst can be removed from the reaction zone and regenerated.Preferably, the catalyst removed from the reaction zone is contacted orwashed with a solvent for polyolefins to remove any occluded ordissolved polyolefin contained on the catalyst. Examples of suitablesolvents include the aforementioned hydrocarbons. Thereafter thecatalyst is drained, the solvent is evaporated therefrom and thecatalyst is then regenerated by contacting with oxygen in accordancewith conventional regeneration techniques. These techniques includecontacting of the catalyst with a gas containing from 0.5 to aboutpercent oxygen at temperatures from about 350 to about 1000 F. toinitiate combustion of any of the high molecular weight product on thecatalyst. This regeneration is performed for a period of from 0.1 toabout 5 hours, suflicient to deplete the catalyst of its carbon content.Thereafter the catalyst is subjected to the aforementioned hydrogenpretreatment prior to contacting with the hydrocarbon reactants.

The invention will now be described by reference to specificallyillustrated modes of practice thereof:

Example 1 A catalyst comprising 0.5 weight percent palladium impregnatedwith an ion exchange procedure on a Y molecular sieve zeolitic catalystwas employed in this example. The preparation of the catalyst comprisedthe preparation of a sodium Y type zeolite having a silica to aluminamol ratio of about 4.7. The sodium zeolite was ion exchanged with anaqueous solution of ammonium chloride to exchange the sodium cationswith ammonium and reduce the sodium content, expressed as the oxide, toabout 2 percent by weight. The resulting ammonium zeolite was thenpartially back ion exchanged by contacting with an aqueous magnesiumsulfate solution to obtain a zeolite having a magnesium contentexpressed as magnesium oxide of about 5 weight percent. The resultingammonium-magnesium zeolite was then further ion exchanged with anaqueous solution of tetraamine palladium chloride to add 0.5 weightpercent of palladium to the catalyst by ion exchange. The final zeolitewas then filtered, drained and dried at a temperature below 400 F. to awater content of about weight percent and then compressed in a tabletingmachine to form As-inch pellets. The pelleted catalyst was then calcinedin dry air for about 16 hours at 950 F. to convert themagnesium-ammonium-palladous zeolite to magnesium-hydrogen-palladiurnzeolite with about 50 percent of the ion exchange capacity satisfied byhydrogen 10m.

The catalyst was treated with the hydrogen by admixing portions of theparticulate catalyst with an equal volume of quartz chips and placingthe admixture in a tubular reactor having means for the introduction andremoval of liquid and vapor reactants. The catalyst was pretreated inthe reactor that was used for the subsequent conversion of the olefin byintroducing hydrogen to flow downwardly through the packed catalyst bedin the reactor.

Upon completion of the aforementioned activation treatments, thecatalyst was then employed for the production of higher molecular weightproducts from olefins.

In a first experiment, the reactor was charged with the aforeindicatedquantities of catalyst and quartz chips, heated to 700 F. and hydrogenwas slowly passed through the catalyst at 50 p.s.i.g. pressure. Thetreatment with hydrogen was continued for 2 hours and the catalyst wasthen cooled to about 150 F. and ethylene was introduced at 500 p.s.i.g.at a rate of milliliters per minute, diluted with heptane that wasintroduced at a rate of 50 milliliters, liquid volume, per hour. Theethylene and heptane were passed through the reactor at theaforeindicated conditions for a period of 4 hours. The vapor effluentfrom the reaction zone was passed through an acetone-dry ice cooled trapto condense any liquid product therefrom. The collected liquid wassampled and analyzed by gas chromatography to indicate that it comprisedchiefiy butenes and hexenes.

Example 2 The reaction was repeated by charging the reactor with freshquantities of catalyst diluted with an equal volume of quartz chips andhydrogen was passed over the catalyst at 300 F. and 500 p.s.i.g. for twohours. Upon completion of the pretreatment, the flow of hydrogen wasceased and ethylene was introduced while maintaining the temperature at300 F. The ethylene was introduced at 1000 milliliters per minute,diluted with heptane introduced at a rate of 50 milliliters, liquidvolume, per hour. The reaction was run for 1 hour and the liquid productcollected in the trap was analyzed by gas chromatography to indicate thefollowing products from the reaction:

Component: Weight percent Butenes 52.6 Hexenes 26.8 Octenes 17.9 Decenes2.7

Oligomerization of other olefins, e.g., of octene-l, can be achieved bysubstituting an equal molar volume of liquid octene-l for the gaseousethylene employed in the preceding example.

Example 3 The experiment was repeated by charging the reaction zone with200 mililiters of the aforeindicated catalyst diluted with 200milliliters quartz chips. The catalyst was treated with hydrogen bybypassing hydrogen over the catalyst at 500 p.s.i.g. at F. For a periodof about 2 hours. Thereafter the hydrogen fiow was ceased and ethylenewas introduced into the reaction zone while maintaining the temperatureat 167 F. and the reactor pressure at about 450 p.s.ig. The ethylene wasintroduced at a rate of 100 milliliters per minute, diluted with heptaneintroduced at 60 milliliters, liquid volume, per hour. The reaction wascontinued for 2 hours and a sample of the product collected in thecondensate trap was analyzed by gas chromatography and mass spectra. Itwas found that the product contained over 99 percent of saturatedhydrocarbons, both parafiinic and mononaphthenic, and the carbon numberdistribution was as follows:

Component: Weight percent C 7.5 O; 4.6 C 15.0 c 34.8 C 18.7 C 12.3 0 3.4C 3.7

Alkylation of propane can be achieved using the same procedure simply bysubstituting an equal molar volume of propane in gaseous state for theliquid heptane introduced in the preceding example.

Example 4 The reaction was repeated by charging 100 milliliters of thecatalyst aforedescribed and 100 milliliters quartz chips in intimateadmixture to the reactor. The reactor was then pressured to 50 p.s.i.g.with hydrogen and hydrogen was passed through the catalyst for 2 hoursat 73 F. The hydrogen flow was then discontinued and the catalyst washeated to 150 F. and ethylene was introduced at 500 p.s.i.g. Theintroduction of the ethylene initiated a rapid exothermic reaction whichrequired cooling to reduce the temperature to about 220 F. Uponcompletion of the reaction the catalyst was removed and found to containsubstantial quantities of solid polymer comprising a total of 12 gramshigh molecular weight solid polyethylene. A portion of the liquidproduct recovered in the product trap was sampled and analyzed to reveala low yield of butenes and hexenes.

The preceding examples are intended solely to illustrate preferred modesof practice of the invention and to demonstrate results obtainablethereby. It is not intended that the examples be unduly limiting of theinvention, but instead it is intended that the invention be defined bythe steps, reagents and catalyst components and their obviousequivalents set forth in the following claims.

I claim:

1. A method for the polymerization of ethylene which comprisesimpregnating a palladium salt or ion exchanging palladium from apalladium salt onto a solid, metallic, aluminosilicate zeolite havingpores of substantially uniform diameter from about 4 to 18 angstromunits and a silica to alumina ratio of about 2.5 to 10, calcining theresultant solid in dry air at a temperature from about 700 to 1000 F.for a period of 1 to 24 hours, pretreating the solid by contacting saidsolid with hydrogen for 1 to about 4 hours at a temperature from 0 toabout 100 F., and contacting the solid so pretreated with ethyl- 10 eneat a temperature from to about 500 F. to produce solid polyethylene ofhigh molecular weight.

2. The method of claim 1 wherein said zeolite is a crystallinealuminosilicate having 2. mol ratio of silica to alumina between about 3and 8.

3. The polymerization of ethylene wherein ethylene is contacted, underpolymerization conditions including temperatures from 50 to 500 F. andpressures from to 1000 p.s.i., sufficient to produce solid polyethylene,with a catalyst prepared by impregnating or ion exchanging a palladiumsalt onto a metallic aluminosilicate zeolite having pores ofsubstantially uniform diameter from about 4 to 18 angstrom units and asilica to alumina ratio of about 2.5 to 10, calcining the catalyst indry air at a temperature from about 700 to 1000 F. for a period of from1 to 24 hours and preconditioning the catalyst before contacting it withethylene by contacting it with hydrogen at a temperature from 0 to about100 F. for a period of 1 to about 4 hours.

4. The method of claim 3 wherein from 50 to 98 of the ion exchangecapacity of the zeolite is satisfied by hydrogen.

5. The method of claim 4 wherein said zeolite is a Y molecular sieve.

References Cited UNITED STATES PATENTS 3,277,071 10/1966 Cotton 26094.9D

3,236,762 2/1966 Rabo et a1. 260683.15 R

2,589,189 3/1952 Ciapetta et a1. 260683.15 R

3,393,251 7/1968 Fenton 260-683.15 R

2,656,398 10/1953 De Vault 260-683.15 R

FOREIGN PATENTS 624,931 8/1961 Canada 260-949 D JOSEPH L. SCHOTON,Primary Examiner E. J. SMITH, Assistant Examiner US. Cl. X.R. 260-93.7,94.9 D

